P656: INCIDENT VENOUS THROMBOEMBOLISM (VTE) IN PATIENTS WITH MONOCLONAL B-CELL LYMPHOCYTOSIS (MBL) AND CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) – A POPULATION-BASED STUDY
Authors: A. Koehler, M. Moise, T. Call, K. Rabe, S. Achenbach, D. Crusan, K. Bailey, T. Petterson, W. Ding, S. Kenderian, J. Leis, Y. Wang, E. Muchtar, P. Hampel, S. Schwager, S. Slager, N. Kay, A. Ashrani, S. Parikh
Journal: HemaSphere (2022)

Background: Data on risk of VTE after MBL/CLL diagnosis is limited;it is unclear if MBL/CLL truly confers increased risk of VTE as seen in other malignancies. Aims: To determine incidence of VTE after MBL/CLL diagnosis and compare it to age- and sex-matched VTE incidence in the general population. Methods: We identified all individuals with newly diagnosed, untreated MBL or CLL between 1998-2021 within a 27-county region surrounding Rochester, MN. Patient demographics and CLL-specific characteristics were extracted from the Mayo Clinic CLL Database and the electronic health record (EHR). Incident VTE after diagnosis of MBL/CLL was identified by querying a) the Mayo Clinic CLL Database; b) EHR for VTE-specific ICD-9 and ICD-10 diagnosis codes; and c) all radiographic studies performed during longitudinal care of these patients. Risk of VTE was estimated using Cox proportional hazards model with CLL/SLL status as a time-dependent variable. The unadjusted cumulative risk of VTE was estimated using Kaplan-Meier methods in SAS 9.4. Rate of incident VTE among age- and sex-matched population residing in Olmsted County, MN from 2001-2015 was pulled from the Rochester Epidemiology Project. Age- and sex-specific VTE risk associated with MBL/CLL (standardized incidence rate ratio; SIR) was estimated by dividing observed post-MBL/CLL diagnosis VTE incidence rate by expected VTE incidence rate in the general population. We performed an exact binomial test in the statistical package R (version 4.1.2) to evaluate whether the proportion of VTE cases after MBL/CLL diagnosis (versus those occurring in the general population) was consistent with their respective proportion of person-years at-risk for VTE. Results: We identified 946 patients with newly diagnosed MBL/CLL, of whom 42 (4%) reported a prior history of VTE and were excluded from this analysis. Of the 904 evaluable subjects, 293 had MBL and 611 had CLL. The median age was 69 years (range, 28 - 96 years) and 587 (65%) were male. After a median follow-up of 6 yrs (range: 1 day-23 yrs), 70 of 904 patients developed VTE after MBL/CLL diagnosis; 43 (61%) with deep vein thrombosis (DVT), 24 (34%) with pulmonary embolism (PE), and 3 (4%) with both DVT and PE as the first event. Risk of VTE was similar in CLL compared to MBL [HR (95% CI) = 0.90 (0.49-1.65)]. The 5-year and 10-year cumulative risk of VTE was 4.9% and 11.5%, respectively. Forty-seven (68%) patients had an identifiable provoking factor apart from MBL/CLL including second active malignancy (n=21), surgery (n=9), recent hospitalization (n=6), travel (n=4), trauma (n=3), line-associated VTE (n=3), and immobility (n=1). The age-adjusted VTE incidence rates for females and males with newly diagnosed MBL/CLL were 1275 and 1228 per 100,000 person-years, respectively. In contrast, the age-adjusted VTE incidence rates for females and males residing in Olmsted County, MN were 193 and 218 per 100,000 person-years, respectively. The overall VTE incidence rate in females and males after MBL/CLL diagnosis was 6.0 (95% CI: 4.0-8.8) and 5.7 (95% CI: 4.1-7.7) higher, respectively, compared to the general population; the risk of VTE was highest in 18–49-year-old MBL/CLL patients (SIR: 16.2, 95% CI: 3.3-47.6) (Figure 1). Image:Summary/Conclusion: In this large population-based cohort study, 1 in 12 patients with MBL/CLL developed VTE after a median follow-up of 6 yrs. Patients with MBL/CLL demonstrated a 6-fold increased risk of VTE compared to the age- and sex-matched general population. Importantly, nearly 3 in 4 MBL/CLL patients had additional provoking factors at time of VTE, most notably second active malignancy.